1. Technical Field
The present invention relates generally to a portable transmitter which transmits operating instructions in the form of a radio wave to a controlled device installed, for example, in an automotive vehicle.
2. Background Art
Japanese Patent First Publication No. 6-252782 discloses a portable transmitter which transmits start instructions in the form of a radio wave to an engine installed in a two-wheel vehicle such as a motorcycle. The portable transmitter has two pushbutton switches installed in opposed ends of a casing thereof. The pushbutton switches are electrically connected in series with each other. Only when the pushbutton switches are both placed in an on-state simultaneously, the portable transmitter outputs the start instructions in the form of a radio wave to the vehicle to start the engine. This minimizes errors in manual operation of the pushbutton switches.
An automotive lift-up seat 200, as illustrated in FIG. 7(a), and a portable transmitter which transmits operating instructions in the form of a radio wave to the vehicle to swivel or rotate the lift-up seat 200 out of the vehicle and lower it to ground or retract the lift-up seat 200 inside the vehicle are known. FIG. 7(b) illustrates such a type of portable transmitter 100.
The portable transmitter 100 includes a casing 110, a retracting switch 112a, and a rotating-and-lowering switch 112b which are disposed on the same surface of the casing 110. The retracting switch 112a is used to retract the lift-up seat 200 into the vehicle. The rotating-and-lowering switch 112b is used to extend the lift-up seat 200 out from the vehicle. The retracting switch 112a and the rotating-and-lowering switch 112b are each implemented by a pushbutton switch which is to be turned on manually by a user. When the retracting switch 112a or the rotating-and-lowering switch 112b is held down, the portable transmitter 100 transmits a radio signal carrying a retracting or a rotating-and-lowering instruction to the vehicle. The lift-up seat 200 is then moved into or out of the vehicle according to a received one of the instructions. When the retracting switch 112a or the rotating-and-lowering switch 112b is released, the portable transmitter 100 stops transmitting the radio signal. The lift-up seat 200 then stops A certain period of time (e.g., 40 sec.) is required between the start and completion of movement of the lift-up seat 200. The user needs to hold the retracting switch 112a or the rotating-and-lowering switch 112b down for that period of time.
The operations of the portable transmitter 100 and the lift-up seat 200 will be described below in detail with reference to FIGS. 8(a) to 8(c).
When the retracting switch 112a is depressed, as indicated by a solid line in FIG. 8(a), by the user at time t101, the portable transmitter 100 simultaneously transmits, as indicated by a solid line in FIG. 8(b), a radio signal carrying the retracting instruction to the lift-up seat 200. At time t102, the lift-up seat 200 is responsive to the radio signal and, as indicated by a solid line in FIG. 8(c), starts to retract inside the vehicle. The lift-up seat 200 completes the retraction at time t105. The user visually perceives the completion of retraction of the lift-up seat 200 and then releases the retracting switch 112a at time t106. The portable transmitter 100 stops transmitting the ratio signal to the lift-up seat 200. In this way, the user keeps the retracting switch 112a held down for a period of time from time t101 to time t106.
As indicated by broken lines in FIGS. 8(a) to 8(c), when the user stops holding the retracting switch 112a down at time t103, the portable transmitter 100 almost simultaneously stops transmitting the radio signal of the retracting instruction to the lift-up seat 200. The lift-up seat 200 then stops retracting inside the vehicle. Afterwards, when the user restarts holding the retracting switch 112a down at time t104, the portable transmitter 100 restarts transmitting the radio signal of the retracting instruction to the lift-up seat 200. The lift-up seat 200 then restarts retracting into the vehicle.
As apparent from the above, the user has to continue to hold the pushbutton switch (i.e., the retracting switch 112a or the rotating-and-lowering switch 112b which will also be referred to as tact switch below) down from when the radio signal starts to be transmitted to give the lift-up seat 200 the operating instruction until the completion of the operating instruction. The keeping the tact switch held down is not quite a burden on physically unimpaired persons, but on physically impaired persons that are most of users of the lift-up seat 200.
In order to alleviate the physical burden of manipulating the tack switch on the users, the portable transmitter 100 may be designed to continue to transmit the radio signal upon holding down of the tack switch for a short time (e.g., 1 sec.). This, however, may result in the following risk. If the user drops and loses the portable transmitter 100 after the lift-up seat 200 has started to move in response to the operating instruction from the portable transmitter 100, it will result in impossibility of stopping the lift-up seat 200 urgently.
In order to alleviate the physical burden on the users, the retracting switch 112a and the rotating-and-lowering switch 112b may alternatively be implemented in place of pushbutton switches by touch switches which are to be touched by the user to operate. The tough switches, however, need be supplied with electric power to operate at all the time, thus resulting in a decrease in operating life of a battery of the portable transmitter 100.
The above problem is thought of as also being encountered in automotive power sliding door systems or power backdoor systems designed to operate for a period of time in which operating instructions, as outputted from the portable transmitter through a radio wave, are received.